Search Results (378)

Metallaphotoredox catalysis merges the powerful bond-forming abilities of transition metal catalysis with unique electron or energy transfer pathways accessible in photoexcited states, injecting new vitality into organic synthesis. However, most transition metal catalysts cannot be excited by visible light. Thus, prevalent metallaphotoredox catalytic systems require dual catalysts: a transition metal catalyst and a separate photosensitizer. This leads to inefficient electron transfer between these two low-concentration catalytic species, which often limits overall photocatalytic performance. Single-atom site catalysts (SASCs) offer a promising solution, wherein isolated and quasi-homogeneous transition metal sites are anchored on heterogeneous supports. When semiconductors are employed as the support, the photosensitive unit and transition metal catalytic site can be integrated into one system. This integration switches the electron transfer mode from intermolecular to intramolecular, thereby significantly enhancing photocatalytic efficiency. Furthermore, such heterogeneous catalysts are easier to separate and reuse. This review summarizes recent advances in the application of SASCs for photocatalytic organic synthesis, with a particular focus on elucidating structure–activity relationships of the single-atom sites. Full article

In this explorative work, molybdenum trioxide (MoO₃) and representative doped MoO₃ materials, i.e., Cu-doped MoO₃ (2% Cu, “Cu-MoO₃”) and H-doped MoO₃ (H_0.31MoO₃, “H-MoO₃”), have been tested for the first time as photocatalysts in the UV-vis light-driven depolymerization of lignin. The catalysts have been characterized by XRD, TEM, ATR-FTIR, and UV-vis DRS. Under the adopted conditions (UV-vis irradiation, solvent 0.01 M aqueous NaOH, lignin 200 ppm, catalyst 1 g/L, rt, 5 h), photocatalytic depolymerization of wheat-straw lignin (WSL) produced increasing amounts of bio-oil on changing the catalyst from pristine MoO₃ to Cu-MoO₃ and H-MoO₃ (23%, 28% and 30%, respectively). Also, quantification of vanillin and vanillic acid shows a similar increasing trend. These results appear in line with the estimated band gap energies, which decrease in the order: MoO₃ (2.91 eV) > Cu-MoO₃ (2.86 eV) > H-MoO₃ (2.77 eV). H-MoO₃ shows the best catalytic performance, which was then fruitfully explored in the photocatalytic depolymerization of benchmark commercial Kraft lignin (bio-oil yield 32%, vanillin and vanillic acid yields 1.28% and 0.78%, respectively). In view of the results obtained, this work is expected to provide new ideas for the design of heterogeneous photocatalytic system for lignin cleavage. Full article

The escalating global water crisis demands the development of cost-effective and environmentally sustainable treatment technologies. Among various advanced oxidation processes (AOPs), peracetic acid (PAA) has emerged as a promising oxidant, owing to its high redox potential, chemical stability, and potent disinfection capability. Nevertheless, the lack of highly efficient catalysts remains a major obstacle to achieving the effective degradation of contaminants of emerging concern in wastewater. Heterogeneous catalysis has proven to be a viable strategy for enhancing PAA activation, highlighting the urgent need for catalysts with superior activity, stability, and recyclability. Metal–organic frameworks (MOFs), with their large surface areas, tunable porosity, and structural diversity, provide versatile platforms for catalyst design. Recently, MOF-derived materials have attracted increasing attention for PAA activation, offering a new frontier in advanced oxidation technologies for efficient and sustainable wastewater remediation. This review systematically examines the role of MOFs in PAA activation, from pristine frameworks to MOF-based composites and MOF-derived catalysts. Mechanistic insights into PAA activation are highlighted, strategies for engineering MOF-based composites with synergistic catalytic properties are discussed, and the transformation of MOFs into robust derivatives with improved stability and reactivity is explored. Special attention is given to the identification and quantification of reactive species generated in PAA systems, providing a critical understanding of reaction pathways and catalytic performance. Finally, current challenges and future directions are outlined for designing highly efficient, recyclable, and environmentally compatible MOF-based catalysts, emphasizing their potential to significantly advance PAA-based AOPs. Full article

The development of sustainable catalysts is the main objective in green chemistry approaches. In this study, a catalytically active polymer based on a tertiary amine was synthesized, functionalized with a photo-crosslinker, and structured into nanofibers via electrospinning technique with polycaprolactone (PCL) as a stabilizing additive. Subsequent photo-crosslinking yielded hierarchically porous polymers with high swelling properties and increased surface areas, thereby improving the accessibility of the immobilized catalytically active sites. The nanofiber mats were incorporated into a microfluidic reactor (MFR) setup and utilized as heterogeneous catalysts for the Knoevenagel reaction of malononitrile with different aldehydes. It was observed that the system demonstrated a substantial improvement in NMR yields (40–60%) and turnover frequencies (50–80 h⁻¹) in comparison to catalytical systems that had been previously published. Reusability studies showed reproducibility of NMR yields over up to three cycles. The obtained results demonstrate the potential of electrospun, photo-crosslinked nanofibers as efficient heterogeneous catalysts in microfluidic synthesis, thus contributing to more sustainable production of valuable malononitrile derivatives. Full article

Copper-based electrocatalytic materials with high surface area are essential for various processes, such as water splitting and the electroreduction of carbon dioxide and nitrates. Three-dimensional nanostructured electrodes offer distinct advantages in these applications due to their expansive surface area, which enhances charge transfer and mass transport. For bimetallic systems, however, the phase state, whether a solid solution or a mechanical mixture of metals, is critically important for catalytic performance. This study explores the formation of Cu-Ni solid solutions via electrodeposition using the dynamic hydrogen bubble template method. Two types of electrolyte were employed: sulfate-based and citrate-based. Through characterization by X-ray diffraction, scanning electron microscopy, elemental mapping, and X-ray fluorescence spectroscopy, we demonstrate that metallic foams deposited from sulfate solutions are heterogeneous, with poor control over nickel content. In contrast, the use of citrate-based solutions allows the nickel content in the deposits to be effectively controlled by varying the solution composition, thereby enabling the formation of a solid solution. Full article

To address the challenges of difficult recovery, significant environmental hazards associated with homogeneous catalysts, and insufficient catalytic activity of heterogeneous supports in the catalytic dehydration of fructose to produce 5-hydroxymethylfurfural (5-HMF), this study employs a straightforward nitric acid modification method to prepare an acid-activated silica gel catalyst for application in this reaction system. Through systematic investigation of the influence of modification conditions on catalyst performance and economic benefits, optimal reaction conditions were determined: DMSO as the solvent, nitric acid-modified silica gel as the catalyst, a reaction temperature of 120 °C, a solid–liquid ratio of 1:30 (g∙mL⁻¹), and a fructose-to-catalyst mass ratio of 1:1. Under these conditions, the maximum 5-HMF yield reached 91.6%. Characterization via specific surface area, pore size analysis, and acid/base site characterization (NH₃-TPD) revealed that nitric acid modification preserved the silica gel’s pore structure. Through oxidative cleaning, etching to expose silanol groups, and inducing surface defects, this process significantly increased the number of acid sites on the silica gel surface, thereby enhancing catalytic activity. This study presents a low-cost, easily recoverable, and environmentally friendly heterogeneous catalytic strategy for the efficient conversion of fructose into 5-HMF. It also provides experimental guidance for the targeted functionalization of silica-based catalytic materials, holding significant implications for advancing the high-value utilization of biomass resources. Full article

Antibiotic resistance (AR) has long been interpreted through the lens of genetic mutations and horizontal gene transfer. Yet, mounting evidence suggests that epigenetic regulation, including DNA and RNA methylation, histone-like proteins, and small non-coding RNAs, plays a similarly critical role in bacterial adaptability. These reversible modifications reshape gene expression without altering the DNA sequence, enabling transient resistance, phenotypic heterogeneity, and biofilm persistence under antimicrobial stress. Advances in single-molecule sequencing and methylome mapping have uncovered diverse DNA methyltransferase systems that coordinate virulence, efflux, and stress responses. Such epigenetic circuits allow pathogens to survive antibiotic exposure, then revert to susceptibility once pressure subsides, complicating clinical treatment. Parallel advances in CRISPR-based technologies now enable direct manipulation of these regulatory layers. CRISPR interference (CRISPRi) and catalytically inactive dCas9-fused methyltransferases can silence or reactivate genes in a programmable, non-mutational manner, offering a new route to reverse resistance or sensitize pathogens. Integrating methylomic data with transcriptomic and proteomic profiles further reveals how epigenetic plasticity sustains antimicrobial tolerance across environments. This review traces the continuum from natural bacterial methylomes to engineered CRISPR-mediated epigenetic editing, outlining how this emerging interface could redefine antibiotic stewardship. Understanding and targeting these reversible, heritable mechanisms opens the door to precision antimicrobial strategies that restore the effectiveness of existing drugs while curbing the evolution of resistance. Full article

Forests are crucial for achieving carbon neutrality and the Sustainable Development Goals (SDGs). This study contributes to SDG 13 (Climate Action) and SDG 15 (Life on Land) by constructing a comprehensive evaluation system for high-quality forestry development (HQDF), integrating economic efficiency, ecological functions, and social benefits. Using provincial panel data for China from 2010 to 2023 and applying two-way fixed effects, panel quantile regression, and instrumental-variable methods, we examine the catalytic role of green finance. The results show that green finance significantly promotes HQDF and displays an inverted U-shaped effect over the development cycle. Regional heterogeneity is marked: the strongest effects appear in western and southern China, moderate effects in central regions, and negative effects in some eastern and northern provinces. Among specific instruments, green investment and green bonds exert the largest positive impacts, followed by green insurance and fiscal funds, while green credit plays an important role at particular stages. These findings provide evidence from a major emerging economy and offer practical guidance for optimizing forestry-related green finance strategies worldwide. Full article

The photo-Fenton process is an advanced oxidation method widely employed in environmental remediation. Herein, we developed a novel metal–organic framework@hydrogen-bonded organic framework (MOF/HOF) composite with excellent photo-Fenton-like activity for the efficient degradation of organic dye methylene blue (MB). Cu-based MOF (CuBTC) was firstly prepared via the solvothermal method, then melamine (MA) and trimesic acid (TMA)-based HOF (MA-TMA) was grown in situ on CuBTC with hydrogen bonding interactions to produce the MOF/HOF composite CuBTC-MA. The CuBTC-MA composite could catalyze H₂O₂ to produce active substances for efficient MB degradation. The degradation rate constant of the CuBTC-MA composite was 4.4 times and 16.7 times higher than that of CuBTC and MA-TMA. The remarkably enhanced performance was attributed to the synergistic effect between the efficient separation of electron–holes supported by the type-II heterojunction structure of the CuBTC-MA composite and the Cu(I)/Cu(II) inter-conversion. The CuBTC-MA composite demonstrated exceptional repeatability and maintained a stable performance across a broad pH range. This study provided a novel paradigm for engineering heterogeneous MOF/HOF heterostructures, demonstrating significant potential in advancing photo-Fenton-like catalytic systems for the efficient environmental remediation of organic pollutants through synergistic charge separation and radical generation mechanisms. Full article

This article presents the design, synthesis and application of novel C₈/PW₁₂O₄₀³⁻-IL Janus for highly efficient, recyclable catalytic degradation of methyl orange (MO) in wastewater. The catalyst’s innovative asymmetric architecture comprises a hydrophobic C₈ hemisphere that selectively adsorbs and pre-concentrates MO molecules and a catalytic phosphotungstate-based ionic liquid hemisphere that activates oxidants to generate hydroxyl radicals for rapid dye degradation. A magnetic Fe₃O₄ core facilitates instantaneous catalyst recovery. This “collect, degrade, and separate” mechanism synergistically results in exceptional performance, surpassing that of many conventional homogeneous and heterogeneous systems, as validated through comparative analysis. This work establishes a strategic paradigm for designing smart, multifunctional materials that combine targeted interfacial engineering with practical recyclability for advanced environmental remediation. Full article

Tetracycline (TC) is chemically stable and recalcitrant to natural degradation. Peroxymonosulfate (PMS)-based advanced oxidation processes offer an effective removal strategy, the efficacy of which relies on high-performance heterogeneous catalysts. Titanium dioxide (TiO₂) is an ideal material due to its stability and environmental compatibility, yet its practical application is hindered by inadequate PMS activation capacity, particle agglomeration, and difficult recovery. To address these limitations, a heterogeneous Fe/TiO₂ catalyst was constructed via Fe³⁺ doping, innovatively utilizing polyvinylpyrrolidone (PVP) as a structure-directing agent. PVP’s steric hindrance effectively suppressed nanoparticle agglomeration and enabled high dispersion of Fe active sites, simultaneously enhancing catalytic activity and stability. Under optimized conditions, the Fe/TiO₂/PMS system achieved 94.3% TC degradation, following pseudo-first-order kinetics and significantly outperforming pure TiO₂ used in this experimental system. Radical quenching verified sulfate radicals (SO₄•⁻) as the dominant species. The catalyst demonstrated excellent recyclability, retaining over 80% degradation efficiency after six cycles and enabling convenient magnetic separation. Moreover, in complex water matrices (tap water and seawater), it sustained high removal efficiency (>90% initially, >70% after six cycles), highlighting its superior anti-interference capability and practical potential. This work offers a strategic material design strategy for efficient and robust TC removal in challenging water environments. Full article

The pervasive discharge of synthetic dyes into aquatic ecosystems poses a significant threat due to their chemical stability, low biodegradability, and carcinogenicity. Conventional dye remediation methods—such as biological treatments, coagulation, and adsorption—have demonstrated limited efficiency and poor reusability, particularly against resilient azo dyes. Cerium oxide (CeO₂) nanoparticles have gained traction as photocatalysts owing to their redox-active surfaces and oxygen storage capabilities; however, issues like particle agglomeration and rapid charge recombination restrict their catalytic performance. To address these challenges, this study presents the novel synthesis of a graphene oxide–cerium oxide (GO-CeO₂) nanocomposite via a facile in situ hydrothermal approach, using graphite from lead pencils as a sustainable precursor. The composite was structurally characterized using UV–visible spectroscopy, XRD, FTIR, and TEM. The GO matrix not only facilitates uniform dispersion of CeO₂ nanoparticles but also enhances interfacial electron mobility and active site availability. The nanocomposite demonstrated exceptional photocatalytic degradation efficiencies for methyl orange (94%), methyl red (98%), congo red (96%), and 4-nitrophenol (85.6%) under sunlight irradiation, with first-order rate constants significantly exceeding those of pure CeO₂. Notably, GO–CeO₂ retained strong catalytic activity over four degradation cycles, confirming its recyclability and structural stability. Total organic carbon (TOC) analysis revealed 79% mineralization of methyl orange, outperforming CeO₂ (45%), indicating near-complete conversion into benign byproducts. This work contributes a scalable, low-cost, and highly active heterogeneous photocatalyst for wastewater treatment, combining green synthesis principles with improved photodegradation kinetics. Its modular architecture and reusability make it a promising candidate for future environmental remediation technologies and integrated photocatalytic systems. Full article

Diphenylmethane, recently recognized as a candidate for liquid organic hydrogen carrier systems, is traditionally produced by alkylation of benzene with benzyl chloride using homogeneous catalysts. In the current context, the need for a transition toward processes that reduce environmental impact and move toward sustainability has become increasingly evident. In this work, the benzylation of benzene by benzyl chloride using metal–organic frameworks (MOFs) as catalysts is proposed, as alternative materials that combine the advantages of homogeneous and heterogeneous catalysis. Reaction experiments were carried out in an isothermal batch reactor with commercial Basolite C300 and Basolite F300 MOFs, based on Cu and Fe as active species, respectively. The results demonstrate catalytic activity using both proposed catalysts under the studied conditions, with the results of the Fe-based MOF being more favorable, given the greater standard reduction potential of Fe. Compared with their corresponding metal chlorides, the proposed MOFs improve the alkylation activity. Based on a two-step reaction mechanism, a pseudo first-order kinetic model has been developed for the reaction with MOFs as catalysts. The kinetic parameters were obtained by fitting the model to the experimental data, demonstrating good agreement and validating the proposed mechanistic pathway. Full article

Iron-based catalysts for peroxymonosulfate (PMS) and peroxydisulfate (PDS) activation represent a cornerstone of advanced oxidation processes (AOPs) in environmental remediation, prized for their cost-effectiveness, environmental compatibility, and high catalytic potential. These catalysts, including zero-valent iron, iron oxides, and iron-organic frameworks, activate PMS/PDS through heterogeneous and homogeneous pathways to generate reactive species such as sulfate radicals (SO₄•⁻) and hydroxyl radicals (•OH). However, their large-scale implementation is constrained by inefficient iron cycling, characterized by sluggish Fe³⁺/Fe²⁺ conversion and significant iron precipitation, leading to catalyst passivation and oxidant wastage. This comprehensive review systematically dissects innovative strategies to augment iron cycling efficiency, encompassing advanced material design through elemental doping, heterostructure construction, and defect engineering; system optimization via reductant incorporation, bimetallic synergy, and pH modulation; and external field assistance using light, electricity, or ultrasound. We present a mechanistic deep-dive into these approaches, emphasizing facilitated electron transfer, suppression of iron precipitation, and precise regulation of radical versus non-radical pathways. The performance in degrading persistent organic pollutants—including antibiotics, per- and polyfluoroalkyl substances (PFASs), and pesticides—in complex environmental matrices is critically evaluated. We further discuss practical challenges related to scalability, long-term stability, and secondary environmental risks. Finally, forward-looking directions are proposed, focusing on rational catalyst design, integration of sustainable processes, and scalable implementation, thereby providing a foundational framework for developing next-generation iron-persulfate catalytic systems. Full article

Fluoroquinolones are a major issue in aquatic ecosystems due to their persistence, potential to induce antibiotic resistance, and inability to be effectively removed using conventional treatment methods. Several advanced oxidation processes have been studied for their degradation; however, there is still a lack of knowledge about their degradation mechanisms and the precise roles played by reactive species. In this context, the study investigated the heterogeneous activation of persulfate (PS) to degrade fluoroquinolones (FQs), such as moxifloxacin (MFX), in iron-rich soil (Cat) under ultrasound irradiation (US). The analysis of the soil catalyst revealed the presence of quartz (35%), iron oxides (33%), and alumina (26%) as the predominant constituents of the sample. The mineral phase analysis indicated the presence of magnetite, hematite, and alumina. Then, the outcomes of the specific surface area, micropore volume, and total pore volume were determined to be 19 m² g⁻¹, 6 m³ g⁻¹ and 9.10 m³ g⁻¹, respectively. The MFX/PS/US/Cat system demonstrated 89% degradation and 56% mineralization after 300 min. However, the optimized concentrations of i-PrOH, t-BuOH, and CHCl₃ were 50, 100, and 50 mM, respectively, in order to trap the radicals SO₄^•−, OH^•, and O₂^•−. The study examined the individual contributions of SO₄^•−, OH^•, and O₂^•− radicals to the overall process of MFX degradation. The results indicated that SO₄^•− was the primary radical, with a contribution of 52%, followed by OH^• with 43%, and O₂^•− with 5%. Finally, the investigation revealed that laterite exhibited both good catalytic activity and reusability over several cycles. The development of this new process could stimulate the creation of cost-effective technology for water remediation through the effective removal of fluoroquinolones. Full article